Solve for $x$ and $y$ using substitution. ${-x-2y = 11}$ ${y = x+8}$
Explanation: Since $y$ has already been solved for, substitute $x+8$ for $y$ in the first equation. ${-x - 2}{(x+8)}{= 11}$ Simplify and solve for $x$ $-x-2x - 16 = 11$ $-3x-16 = 11$ $-3x-16{+16} = 11{+16}$ $-3x = 27$ $\dfrac{-3x}{{-3}} = \dfrac{27}{{-3}}$ ${x = -9}$ Now that you know ${x = -9}$ , plug it back into $\thinspace {y = x+8}\thinspace$ to find $y$ ${y = }{(-9)}{ + 8}$ $y = -1$ You can also plug ${x = -9}$ into $\thinspace {-x-2y = 11}\thinspace$ and get the same answer for $y$ : ${-}{(-9)}{ - 2y = 11}$ ${y = -1}$